How Do You Write an Indirect Proof?

How Do You Write an Indirect Proof?

Note:

This tutorial looks at using an indirect proof to show that an equilateral triangle cannot have a right angle.

Keywords:

  • problem
  • proof
  • indirect proof
  • equilateral triangle
  • right angle

Background Tutorials

  • Derive and use the distance, slope, and midpoint formulas to verify geometric relationships, including congruence of segments and parallelism or perpendicularity of pairs of lines

      • What are Equilateral, Isosceles, and Scalene Triangles?What are Equilateral, Isosceles, and Scalene Triangles?

      What are Equilateral, Isosceles, and Scalene Triangles?

      Did you know that there are different kinds of triangles? Knowing how to identify these triangles is an important part of solving many problems involving these triangles. Check out this tutorial and learn about some of the different kinds of triangles!

  • Investigate patterns to make conjectures about geometric relationships, including angles formed by parallel lines cut by a transversal, criteria required for triangle congruence, special segments of triangles, diagonals of quadrilaterals, interior and exterior angles of polygons, and special segments and angles of circles choosing from a variety of tools

      • What is the Triangle Sum Theorem?What is the Triangle Sum Theorem?

      What is the Triangle Sum Theorem?

      When you're dealing with triangles, the Triangle Sum theorem can be very useful in finding interior angle measurements. In this tutorial, learn how to find this helpful theorem!

  • Apply the definition of congruence, in terms of rigid transformations, to identify congruent figures and their corresponding sides and angles

      • What is the Substitution Property of Equality?What is the Substitution Property of Equality?

      What is the Substitution Property of Equality?

      If you ever plug a value in for a variable into an expression or equation, you're using the Substitution Property of Equality. This property allows you to substitute quantities for each other into an expression as long as those quantities are equal. Watch this tutorial to learn about this useful property!

  • Verify theorems about the relationships in triangles, including proof of the pythagorean theorem, the sum of interior angles, base angles of isosceles triangles, midsegments, and medians, and apply these relationships to solve problems

      • What are Acute, Obtuse, Right, and Straight Angles?What are Acute, Obtuse, Right, and Straight Angles?

      What are Acute, Obtuse, Right, and Straight Angles?

      Did you know that there are different kinds of angles? Knowing how to identify these angles is an important part of solving many problems involving angles. Check out this tutorial and learn about the different kinds of angles!